This invention relates to flame retardant polyurethane elastomer compositions. More particularly, this invention relates to flame retardant thermoplastic polyurethane elastomer compositions comprising a thermoplastic polyurethane elastomer and a flame retarding amount of the pentate salt of an amino-s-triazine and to a method for rendering thermoplastic polyurethane elastomers flame retardant.
Urethane resin compositions have long been known. The chemistry of these resin systems is well-understood and has been used to provide a wide variety of materials including urethane coatings, foam structures, urethane casting resins and thermoplastic urethane elastomers. Urethane foams have been widely employed in insulation, seating, upholstery, crash pads, as fabric liners and the like. Thermoplastic urethane elastomers, unlike most crosslinked rubbery materials, are readily processible by blow-molding and in extrusion and injection molding equipment. Because of unusual toughness and oil and abrasion resistance, thermoplastic urethane elastomers have found use in such diverse applications as automotive fender extensions and bumpers, roller skate wheels and horseshoes. Urethane resins are, however, generally regarded as flammable, ranging from rapid burning unmodified foam structures to slow-burning molded goods. Urethane elastomers also tend to degrade during burning to produce very low viscosity molten materials which tend to drip badly and spread the fire through flaming droplets. The use of flame retardants in urethane compositions is therefore indicated where flame retardant properties are required.
Flame retarded polyurethane elastomer compositions containing halogen compounds or phosphorus compounds which exhibit self-extinguishing, UL V-O characteristics are known. For some applications, however, the use of halogen- or phosphorus-based additive flame retardants is not desirable. Some phosphorus compounds, for example, tend to plasticize polymers and alter the physical properties. Similarly, halogen-based flame retardants, whether used alone or in conjunction with synergists such as antimony oxides may alter key physical properties of the resin and limit the potential enduses. An alternative flame retardant for use in these resins would thus broaden the choices available to the resin compounder for meeting the demands of the market.